Raman and infrared spectroscopic studies and conductivity and viscosity measurements of propylene carbonate (PC) doped with various concentrations of lithium perchlorate are reported. The assignment of the vibrational modes was supplemented by AM1 normal coordinate analysis. Both Raman and infrared spectra showed band splitting in the fundamental vibrational frequencies of PC and perchlorate anion. Spectral curve fitting within the totally symmetric perchlorate band shape showed contributions of free ion, solvent-shared ion pairs, and contact ion pairs. Strong Li+-PC interaction was observed for the PC ring deformation band at 712 cm-l. Ion pairing as deduced by spectroscopic techniques provided a rationale to account for conductivity and viscosity data.

The anion ClO 4 -and the ion pair of Li + ClO 4 -have been studied by ab initio quantum chemical methods. Optimized geometries for monodentate, bidentate, and tridentate structures have been determined up to the MP2/6-311+G* level of theory. Vibrational frequencies were determined for the ClO 4 -anion and the Li + ClO 4 -ion pair up to the HF/6-311+G* level of theory. Comparisons are made with experimental Raman spectra of electrolyte solutions. At the highest level of theory, the bidentate structure was found to be preferred over monodentate or tridentate configurations.

The infrared and Raman spectra of perchlorinated phthalocyanine (Pc), H2PcCI,, , LuPc,CI,, and the unsymmetrical LuPc,CI,, are reported. The vibrational data set also include SERRS and the far-infrared spectra between 100 and 400 cm-'. The vibrational assignment of characteristic wavenumbers was supported by a semiempirical calculation using the PM3 Hamiltonian. The H,Pc molecule was used as a reference in the PM3 vibrational calculations. The effect of the chlorine substituents on the optical spectra of the phthalocyanine ring is examined. I N T R O D U C T I O NIn early work, Kluiev et al.' studied the mid-infrared spectra of chloro derivatives of metallated phthalocyanine (Pc) molecules in KBr pellets. In their work, the C-Cl stretching vibrations in tetrachloro-CuPc were assigned to wavenumbers observed at 632, 698,700, 825 and 835 cm-'. However, the interpretation of vibrational wavenumbers in the perchlorinated molecule was not attempted, but it was asserted that the infrared spectrum of the latter was much simpler than that of the other derivatives. The electronic spectra of Zn, Co and Fe perchlorinated Pc molecules have also been reported., In this paper, the Raman and surfaceenhanced resonant Raman scattering (SERRS) spectra of H2PcCl,, , LuPc,Cl,, and the unsymmetrical LuPc2c116 are reported for the first time. Using infrared and Raman data and with the help of semi-empirical calculations, the observed characteristic vibrational wavenumbers were successfully assigned and the effect of chlorination on the vibrational spectra was examined. EXPERIMENTALChlorinated phthalocyanines (HzPcCl, 6, LuPc,c1,6 and LuPc2C1,,) were kindly supplied by Dr L. Tomilova. Samples were prepared in KBr pellets for Raman and mid-infrared experiments and in Nujol mulls for far-infrared measurements. The materials are insoluble in all common organic solvents, which prevented the fabrication of monomolecular films. Cast films of H,PcCl,, were prepared on Ag films from emulsions in chloroform for reflection-absorption infrared experi-* Author to whom correspondence should be addressed. 0377-0486/93/12~3-M sO8.M) 0 1993 by John Wiley & Sons, Ltd.ments. Similarly, cast films were used to observe SERRS on gold island films., A Spectra-Physics Model 2020 krypton ion laser was used to obtain inelastic scattering, which was measured with a Spex-1403 double spec-. trometer. A Lexel argon ion laser was used to excite the non-resonance spectra measured with a THR-3000 spectrograph equipped with a liquid nitrogen-cooled Spex CCD detector. Infrared spectra were measured on a BOMEM DA3 Fourier transform (FT)IR spectrometer equipped with an MCT detector and a DTGS pyroelectric detector operating at 300 K. A beamsplitter consisting of a 6 pm stretched Mylar pellicle was used for the far-infrared measurements. For data analysis, all files were imported to Spectra Calc software available from Galactic Industries. CalculationsSemi-empirical methods provide useful complementary information in the assignment of vibrational wavenumbers in large mole...